1. Field of the Invention
This invention relates to an apparatus and method for monitoring, recording, and reporting the channels to which a Cable Television (CATV) user is tuned.
2. Description of the Related Art
Cable Television (CATV) has come to play a dominant role in the television industry of the United States and other countries. It has proven attractive to viewers wishing to receive more than the handful of the television signals normally within range for over-the-air television transmission (in the Very High Frequency, VHF, and Ultra High Frequency, UHF, ranges). In addition to signals originally transmitted over the air by television stations all around the country, CATV subscribers generally have access to closed circuit broadcasts including those of movies, sports events, and other special features. Indeed, entire new television networks transmitting only over cable have grown up in response to the spread of CATV.
CATV companies typically bill their subscribers a flat monthly fee in exchange for a certain basic set of channels including over-the-air stations, Cable News Network (CNN), The Weather Channel, and anything else the particular operator decides to supply. These basic channels are available to the subscriber 24 hours a day, regardless of actual use, for a particular contract period (typically a month). For an additional monthly fee the subscribers can receive supplemental channels-such as HBO. Finally, there are Pay-Per-View (PPV) programs available that subscribers can request and pay for on an individual show basis, if available through the particular operator. To receive a pay-per-view, typically the user must contact the CATV originator in order to request that the desired transmission be made accessible-e.g., by the originator unscrambling a normally scrambled transmission, with the attendant incorporation of specialized equipment in the house.
Another way to characterize the flat monthly fee is to state that the subscriber has to pay this fee even if no one in the subscribing household watches any of the CATV programs during the month for which the fee is charged. One reason for this flat fee arrangement has been the general inability of CATV originators to dependably monitor the subscriber's normal day-to-day channel-by-channel usage. This has not been because of a lack of availability of a two way communication system between the CATV originator and each individual subscriber. Indeed, much of the modern operation of "pay-TV"-as indicated above-has depended upon there being some way for 1) the subscriber to electronically order special programs in advance, and 2) for the CATV originator to ensure that an individual subscriber requesting a particular program receives that program. Nevertheless, this two-way communication has remained very limited and has generally required some participation on the part of the subscriber.
The most common technique (see, e.g., U.S. Pat. No. 4,752,954 issued 1988 to MASUKO) for this two-way communication has called for a "polling command signal" to be sent out periodically by the CATV originator, a command designed to elicit a specific response in a single subscriber's in-house cable box. The response sought is a short burst of "upstream" data regarding program requests, billing, and the like which has accumulated since the previous polling signal to that cable subscriber box. The data is processed for each subscriber in turn by circuitry at the CATV originating center. A means must be in place to enable the originator to distinguish one upstream data packet from another.
It is in the nature of the conventional polling system that the data sent upstream has been affirmatively entered at some prior time by a deliberate, discretionary act of the subscriber through the in-house PPV cable box. Although this approach is satisfactory for dealing with orders from the subscriber for limited selective service, it is not practicable for the broader collection of information, especially billing information across the full channel selectivity, which the individual subscriber will not have either the incentive nor the means to provide.
Another approach to providing communication between subscriber and CATV originator has been to suggest the use of local oscillator frequencies generated by the subscriber's television set.
In a cable system, the specific channel frequency allocations are at a separation of 6 MHz starting at 54 MHz and progressing to 546 MHz for a 82 channel system. With even a moderately loaded cable system, of 10 to 20 channels, it is virtually impossible to discriminate the local oscillator frequencies from the channel carrier frequencies, and the intermodulation frequencies. The noise level on the cable also precludes reliable detection of the local oscillator frequency of all channels for a representative set of receivers. It was indicated by FULMER, et al. U.S. Pat. No. 4,723,302 issued on Feb. 2, 1988, that known techniques for monitoring the local oscillator frequencies were "prone to errors caused by extraneous signals." Fulmer attempted to solve the reliable detection of the local oscillator frequency by attempting to detect the harmonics of the local oscillator frequency and assigning a numeric value to each of the harmonics for some statistical detection. If the local oscillator frequency was difficult to detect, the harmonics are significantly more difficult to detect because of their significantly lower power levels. With vacuum tube superheterodyned receivers, this technique may have been possible because of the larger r-f power required; but with solid state receivers, no harmonics could be detected down to an average noise level of -58 dbmV for a representative set of television receivers.
An across-the-board usage based system for faithfully and automatically recording all usage of individual channels by the individual subscriber and the relaying this information periodically to the CATV originator is not found in the prior art.